Zhone Technologies IMACS Network Device - Manual (Page 49)

Zhone Technologies, Inc. IMACS Product Book, Version 4
March 2001 Page 45
HSU Card
The HSU card allows the connection of high-speed data terminal equipment (DTE) and data communications
equipment (DCE) to WAN links, server cards (FRS) or another HSU card. The HSU card also provides low or mid-
density connectivity for local, synchronous peripherals such as, LAN Bridge/Routers and legacy SNA/SDLC
devices. Additionally, these high-speed data cards provide broadcast functionality for point to multi-point
operations suitable for applications such as video-conferencing. When used in conjunction with an 8840 PRI Server
Card, the HSU card can be used to provide switched data application functionality. All HSU cards can be installed
in any of the User Slots in an IMACS chassis.
Each port on a HSU can be independently configured to operate at speeds of Nx56 or Nx64 Kbps, where N equals 1
to 24 in T1 mode or 1 to 31 in E1 mode. In addition to the data rate, each synchronous port’s Transmit Clock can be
programmed for Internal or External modes and both the Clock and Data Polarity may be inverted through software.
The External Transmit Clock mode and the Inverted Clock Polarity mode may be useful in ensuring that both the
Transmit Clock and the Transmit Data are in sync when they reach the HSU port. This should occur when the HSU
port and the attached device are connected over a long cable. The Data Polarity may be inverted to ensure the
density for Nx64 Kbps data circuits supporting HDLC-based protocols that are connected to non-B8ZS T1 facilities.
The “Clear To Send” control lead may always be set to high, low or local mode. In local mode, the CTS signal
reflects the state of the Request To Send (RTS) signal that is received from the attached DTE device. In that mode,
the delay between RTS and CTS is software set-able, with options of 0, 30, 60 or 100 milliseconds. Additionally, if
the HSU port is programmed to operate at Nx56 Kbps, then RTS will be transmitted end-to-end and presented as
RLSD at the far end of the circuit.
Software-initiated diagnostics support the setting of local loop backs towards either the network or the attached DTE
equipment. Additionally, a remote loop back function allows the HSU card to generate three DDS-compatible
latching loop back codes for the far-end OCU, CSU and DSU equipment. Similarly, the HSU data port may be
programmed to detect and respond to both latching and non-latching DDS-format OCU, CSU and DSU loop back
codes initiated from the remote end of the circuit. A time-out option authorizes the HSU port to automatically
release the loop back after ten minutes. This feature applies to an HSU port that is running at 56 Kbps or for super-
rate circuits if the loop back code is transmitted in the first super-rate’s DSO. The card can also generate and
recognize two industry standard in-band loop-up and loop-down codes that act on the entire super-rate circuit.
Those are the ITU (CCITT) V.54 code and the ANSI Fractional T1 code.
Additionally, the integral Bit Error Rate Tester (BERT) can be used to generate test patterns and route those towards
the WAN facility. These test patterns can then be used to verify synchronization and measure circuit quality. For
further information regarding Performance Monitoring and Diagnostic Capabilities, see Section 13, IMACS System
Testing and Diagnostics.
Applications
There are several business applications the IMACS equipped with an HSU card supports.
LAN to LAN
LAN to WAN to LAN
Work Station to Computer
Computer to Computer
Compressed Video
CAD/CAM
Call Center
IMACS and HSU Application Example
A major Health Maintenance Organization has numerous locations, which have a Central main hospital facility and
smaller satellite facilities. The HMO cannot afford to fully staff each main and satellite site with specialists. As
patients enter the satellite facilities, video and audio sessions can be established with the specialists at the Main